The present invention relates to a method and apparatus for profiling a log, particularly for cutting a reentrant corner in the log that extends along the log.
To process logs into standard lumber, the logs are first slabbed on one to four sides. To avoid waste and, because the cross-section of the log is generally round, this processing intentionally leaves four rounded corners. Referring first to FIGS. 1A and 1B depicting, respectively, the cross-section of the log before and after being slabbed on four sides and then turning to FIG. 1C, the rounded corners are removed by cutting into the log along its longitudinal axis corresponding reentrant corners "C." This squares portions of the log, indicated in the Figure as "A", that are located between the contours of adjacent corners so that the portions are configured to be cut into pieces of standard lumber. Forming the corners C is typically referred to as "profiling" and an apparatus adapted for this purpose is typically referred to as a "profiler."
An example of a prior art profiler is shown in FIG. 2. First and second knives 2 and 4, which are identical, are disposed on the circumference of a rotating disc 6. A slabbed log 8 having an elongate axis "L" is fed toward the disc along a circumferential direction "d." The cutting edge of the first knife is oriented parallel to the axis of rotation of the disc and the cutting edge of the second knife is oriented in a plane of rotation of the disc. Referring back to FIG. 1C, the first knife cuts a first leg "11" of a particular reentrant corner C and the second knife cuts a perpendicular, second leg "12" of the reentrant corner, wherein the legs 11 and 12 meet at a region of intersection "c1" of the corner C. It should be understood that the legs "11" and "12" are the visible portions of planar surfaces extending along the longitudinal axis of the log.
Another example of a prior art profiler replaces the second knife with a sequence of cutting teeth disposed around the periphery of the disc, such as the teeth of a saw blade.
In both of these profilers, the first and second knives are disposed so that the first knife meets the log at a different time than does the second knife. Because there is relative movement between the disc and the log, this time difference provides an opportunity for the two cuts to fail to intersect precisely at the same corner region c1 and thereby fail to form a clean or smooth corner C. In particular, there often results, running longitudinally along the corner C, "feathers" or slivers of wood partially but not completely removed from the log, or other unevenness in the surface texture of the corner. This result is often aggravated further as wear occurs in the apparatus.
Accordingly, there is a need for a method and apparatus for profiling a log that provides for the formation of smoother surfaces in corners cut thereby and for maintaining this capability despite wear in the apparatus.